84 l^HE AMBHICAN MONTHLY [Mar 



bacilli, the spirillum of Asiatic cholera, and the Staphy- 

 lococcus pyoge7ies aureus, with negative results. Prepara- 

 tions of the smegma bacilli were also made, but did not 

 stain with sudan iii, although they were stained with car- 

 bol fuchsine according to the ordinary method. In a 

 mixed preparation of tubercle and smegma bacilli, stain- 

 ed with sudan iii and well washed with seventy-per-cent 

 alcohol, the tubercle bacilli appeared characteristic, while 

 the smegma bacilli remained unstained, although this 

 same preparation, when subsequently stained with carbol 

 fuchsine, showed smegma bacilli present in abundance. It 

 would appear from the results so far obtained that sudan 

 iii may be considered as a selective stain for tubercle 

 bacillus, and that this selective action is due to the large 

 amount of fatty material present in the body of the germ. 

 When stained with sudan iii the characteristic beaded 

 appearance of the tubercle bacilli is very distinct, and, 

 as has been suggested, this beaded appearance in the 

 staining is probably due to the droplets of fatty substance 

 present in the body of the germ. Although smegma ba- 

 cilli stain very readily with carbol fuchsine, similarly to 

 the tubercle bacilli, the fact that the smegma bacilli do 

 not stain with sudan iii would indicate that their cell sub- 

 stance is very different from that of the tubercle bacilli. 



The practical value of sudan iii as a stain for tubercle 

 bacilli will be recognized where a rapid method is desired 

 for staining the organism in tissues and for the purpose 

 of differentiating without trouble between smegma and 

 tubercle bacilli in cases, as in urinary sediments, where 

 the smegma bacilli might be present, and throw some 

 doubt upon a positive identification of the tubercle ba- 

 cilli by the ordinary method of staining. The method 

 takes about the same length of time as the carbol-fuch- 

 sine method for cover-glass preparations, but as the stain 

 is a selective one for tubercle bacilli, it is well adapted to 

 routine work. — Bureau of Animal Industry. 



